Coloring or printing patterns on textile sheets involves applying the desired dye, ink or ink patterns on the front or face of the textile sheet using methods such as spraying, screen transfer, or direct digital printing. The applied ink is expected to propagate toward the back of the textile sheet. If the applied ink does not propagate sufficiently through the depth of the textile sheet towards the back, fibers or yarns in the relatively bulky and deep textile sheet maintain their original color within the lower strata of the sheet. Furthermore, during the printing of a white fabric containing a relatively dense sublayer such as a film that is used to hold the fabric together, the film acts as a barrier, retarding or preventing the flow of ink from the front to the back of the fabric. The result is an undyed white face adjacent the back of the fabric. The undyed lower parts of the fabric can be visible when the face fibers are parted, exposing the bases of the fibers. In addition, the partial visibility or “shine-through” of the undyed portions of the fabric can dilute or modify the desired coloring or printing on the front of the fabric, losing “print sharpness”. Moreover, an undyed layer remains visible under the fabric, and a line free of dye is exhibited at the cross-sectional interface at the cut edges.
Vacuum extraction systems are commonly used in the textile dyeing industry. Conventional vacuum extraction systems remove excess water or other liquid coatings from the fabric, reducing the amount of work in an oven or dryer by decreasing wet pick-up. Using vacuum extractors yields shorter ovens and reduced energy consumption. Vacuum extraction systems are also used to draw inks into and through fabrics. Vacuum rolls and vacuum belts are used under a wet or freshly printed sheet, and improvements to the printing equipment and the suction systems are illustrated, for example in U.S. Pat. Nos. 4,704,028 and 4,056,057. An attempt to concentrate vacuum using a narrow nozzle underneath the dye application zone is described in U.S. Pat. No. 3,536,005. However, vacuum applied to bulkier and thicker fabrics from the back face, at a distance from the front face equaling the thickness or depth of the fabric, is rarefied because of the depth or thickness of the fabric and may not pull the liquid evenly or sufficiently into or through the fabric if the fabric is highly air-permeable. Conversely if the fabric is highly impermeable, vacuum cannot pull sufficient air to help the dye propagate to the inner or back strata. Therefore, merely applying vacuum to a fabric may not achieve uniform penetration of dye into or through the entire fabric.
Therefore, a need exists for an improved method and system for printing relatively thick or bulky textile sheets that provides for the maintenance of a sharp image on the surface and for even and complete propagation of the ink from the front of the fabric face layer into the fabric and optionally to the back of the fabric.